Phosphorus-containing tung oil-based siloxane toughened phenolic foam with good mechanical properties, fire performance and low thermal conductivity
Fei Song, Zhuo Li, Puyou Jia, Caiying Bo, Meng Zhang, Lihong Hu, Yonghong Zhou
Abstract
Phenolic foam (PF) is widely used as exterior-wall insulation material but has poor mechanical properties and high friability. To improve the robustness of PF without sacrificing its inherent advantages, a novel reactive tung oil-based toughener that contains P and Si is synthesized and embedded into the rigid molecular structure of PF as long, flexible chains to fabricate biomass-based PFs (TDKPFs). The introduction of these long, flexible chains effectively improved the compressive and bending strengths, which were almost 180% and 198% that of pure PF, respectively. The TDKPFs had a lower thermal conductivity of 0.0316 W/(m·K), suggesting superior thermal insulation. Notably, these TDKPFs solved the reduction in flame resistance that is caused by the introduction of alkyl long chains and had a high limiting oxygen index of 41.7%. Cone calorimetry tests indicated that the peak heat-release rate of the TDKPFs was reduced by 15.6%. In particular, the total smoke release of the TDKPFs was 7.29 m2/m2, a reduction of 75.8% over pure PF (30.2 m2/m2), indicating superior smoke-suppression. The mechanism analysis revealed that a compact hybrid barrier with rich polyphosphate and silica formed, inhibiting the transfer of heat, O2, and mass during combustion. Thus, TDKPFs have great potential as insulation materials.